1. The patterns of free amino acids determined in the cells and fluid of the Yoshida ascites tumor by two-dimensional paper chromatography were found to be similar to those previously described for other ascites and solid tumors.

  2. A detailed description was given of changes taking place in the content of ninhydrin-reactive constituents in the cells and fluid at various time intervals after the injection of L-glutamine into rats bearing the Yoshida sarcoma. A rapid uptake of this amino acid by the cells was followed by its disappearance from both the cells and fluid.

  3. In contrast to the findings with glutamine, the injection of L-glutamic acid did not result in a notable increase in the glutamic acid content of the tumor cells or in marked changes in the content of the other detectable constituents in the cells and fluid. There was a rapid disappearance of this amino acid from the ascitic fluid. Experiments with dl-glutamic acid-2-C14 showed that the tumor cells possess only a limited permeability to this amino acid.

  4. Experiments with glycine-1,2-C14 and taurine-1,2-C14 showed a rapid uptake of the label by the tumor cells. Some of the glycine entering the cells was converted to serine, glutathione, and unidentified substances. No metabolites of taurine were detected in the tumor cell. However, radioactivity was found in several unidentified substances not reacting with ninhydrin on chromatograms from extracts of ascitic fluid of animals receiving the labeled taurine.

  5. Administration of radioactive sulfate did not result in fixation of S35 into taurine in the cells of Yoshida sarcoma.

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This investigation was supported by research grant C-2568 from the National Cancer Institute, United States Public Health Service.

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